Go to the main menu, select the "My 2K7" option, then choose the "Enter Cheat Code" selection. Now, you can enter one of the following codes:
All bonuses: Derek Jeter
All cheats: Black Sox
All extras: Game On
Mickey Mantle card: themick
Pinch Hit Mick card: phmantle
Big Blast card: m4murder
Mighty Mick card: mightymick
Triple Crown card: triplecrown